The present invention relates generally to the high speed winding of filamentary material onto bobbins or spools to form packages of filamentary material. More particularly, it relates to the handling of man-made filament yarn during the initial stages of winding a package.
The manufacture of man-made or synthetic filament yarns is typically achieved by extruding a molten polymer, such as polyester, polyamide, etc., through hole(s) in a spinneret and then cooling the filament(s) thus formed. Thereafter, the filaments may be gathered together to form a multi-filament yarn and, possibly after further treatment, are wound onto a tube so that a yarn package is formed.
Winding of the yarn is performed mechanically by winders which rotate one or more tubes to wind-up the yarn while traversing the yarn along the tube axis to achieve a uniform thickness of yarn being wound.
A doffing/donning operation (i.e., replacement of the yarn packages with empty tubes on the winder) is often performed manually by an operator who (i) severs the yarn, (ii) stops the rotary drive to the packages, (iii) replaces the packages with empty tubes, (iv) re-establishes the rotary drive between the winder drive head and the tubes, and (v) rethreads the yarn onto the empty tubes. Severing of the filamentary yarn is typically performed with scissors while the inlet of a suction or aspirator gun is held against the yarn at a location above the point of serving. Once the yarn is severed, the trailing end of the yarn is wound onto the yarn package, while the newly formed leading end of the yarn is sucked into the aspirator and fed to a waste collector. The suction gun is then placed onto a holder while the yarn packages are being replaced by empty tubes. When the empty tubes attain full speed, the operator manipulates the suction gun to attach the yarn to the rotating tubes so that this winding operation may begin.
In order to economize such winding operations, it has heretofore been proposed to mechanize the doffing and donning operations to a certain extent by providing a mechanism which automatically severs, aspirates and rethreads the yarn. Exemplary of proposed mechanisms of that type are the disclosures in U.S. Pat. No. 4,023,741 issued to Schar on May 17, 1977; U.S. Pat. No. 4,052,017 issued to Schar on Oct. 4, 1977; and U.S. Pat. No. 4,108,388 issued to Schar on Aug. 22, 1978.
One of the operations to be performed during a typical threading of yarn onto an empty tube is the forming of a so-called yarn "transfer tail" at an end of the tube which enables the end user of the yarn to tie together a series of packages to form a continuous threadline for subsequent uninterrupted yarn processing such as knitting, weaving, creeling, etc. The transfer tail is formed at the beginning of a winding sequence. One manner of forming such a "tail" is to provide a tail making guide on the winder. The tail making guide includes a slot which temporarily captures the yarn before the latter is installed within the pinch groove of an empty tube. The presence of the yarn within the slot prevents the yarn from being picked up by the standard traversing guide, i.e., the yarn is held against movement along the axis of the tube. Accordingly, a so-called "waste bunch" of yarn is wound in close order upon the package. After a preset period, the tailing guide ejects the yarn from the slot and the yarn is picked-up by the traversing guide, thereby forming a "tail" upon the tube. The end user of the yarn cuts the tail from the waste bunch (the waste bunch may constitute yarn which has experienced a tension change during the threading procedure) and ties same to the leading yarn end of another package to form the continuous threadline.
One problem which tends to occur involves a premature egress of the yarn from the slot in the tailing guide. That is, as the yarn is caught in the pinch groove of the empty tube, the initial rotation of the tube causes the yarn to become slackened. This slackening often dislodges the yarn from the slot before a proper waste bunch has been formed.
It is, therefore, an object of the present invention to minimize or obviate problems of the above-discussed sort.
Another object is to prevent premature egress of the filamentary material from a tail making guide.
A further object is to temporarily block yarn from exiting a tail making guide to insure that a proper waste bunch and transfer tail are properly formed.